The above-identified, previously filed, co-pending applications disclose semiconductors formed of catenated phosphorus materials. It is highly desirable that large crystals of these materials be formed for use in electronic and electro-optical devices and as optical rotators. It is also highly desirable that such materials be grown on III-V semiconductors such as gallium arsenide and gallium phosphide to form the I-layer thereof in MIS devices as disclosed in the above-identified co-pending application of Diego Olego, David G. Brock, John A. Baumann, and William E. Spicer entitled MIS DEVICES EMPLOYING ELEMENTAL PNICTIDE OR POLYPHOSPHIDE INSULATING LAYERS filed herewith, which application is incorporated herein by reference.